Sunday, January 31, 2010

A winter hike is good for the body, mind and soul. Cold, clean air, aerobic exercise, solitude and time for reflection are primary benefits. But it is the silence of winter that makes the season especially therapeutic.

Broken only by the rustle of dry oak leaves, the drumming of woodpeckers, the ever cheerful tune of chickadees, the distant clamour of crows and the occasional chirp from sparrows in the trailside thickets, the calm of a winter walk is the best natural cure for the varied stress of life. A hawk may circle overhead, deer may bolt for the woodland and cardinals may flash their bright coats from the hedgerow, but, overall, nature will leave us alone; even the restless flocks of geese, sensing a higher sun, are less vocal during this season of survival.

Despite the general silence and drab landscape, nature's cycle has not shut down. Beneath the dry grass and leaf litter, the bounty of last summer is being recycled and, deep in the forest, great horned owls have begun to nest. Within a few weeks, tree frogs will chirp from the icy shallows and green shoots will appear along our ponds and streams. Silence will then yield to the tide of spring.

Thursday, January 28, 2010

As with terrestrial ecosystems, there are regions of the ocean that teem with fish and their predators while others are marine deserts, harboring little diversity of life. The latter occur in areas of tropical oceans, where there is little mixing of the marine layers and where the warm surface waters retain less oxygen; of course, the deep waters of these marine deserts remain relatively unexplored and, as we have discovered along mid-oceanic ridges (spreading zones), they may harbor unimagined forms of life.

By contrast, colder oceans in the Temperate and Polar regions are relatively rich in oxygen and, where ocean currents encounter island ridges or continental shelves, a diverse web of marine life is supported. Upwelling of deep ocean water brings a steady supply of nutrients to the surface, nourishing krill, the primary consumers of the sea. Fish and baleen whales feed on the krill and they, in turn, are consumed by marine mammals, larger fish, sharks, killer whales and a wide variety of sea birds.

When polar waters freeze over during the winter months, this food chain shuts down and most of the secondary and tertiary consumers migrate to warmer areas. While baleen whales fast during this period, the other migrants head for coastal areas, island chains and reefs where upwelling currents sustain schools of prey. All of this explains why rich, marine fisheries develop where cold ocean currents sweep along the continental shelves; unfortunately, many of these areas are threatened by over-fishing and pollution, potentially resulting in man-induced ocean deserts.

Tuesday, January 26, 2010

Natives of Central and South America, wood storks likely spread northward as the climate warmed following the Pleistocene Ice Age. Inhabiting the Coastal Plain of North America, from Texas to the Carolinas, they favor wooded swamps and marshlands, where they usually nest in large colonies.

Wood storks are easily identified by their large size and white plumage, fringed with black on their wings and tail; their head is gray and unfeathered and their long, thick bill has a slight downward curve. The latter feature led to their former title of "wood ibis" though they are, in fact, a member of the stork family. Moving about in small flocks, wood storks feed on fish and marine invertebrates in the shallows of coastal bays or hunt for frogs, lizards, small rodents and insects across freshwater wetlands.

Since they prefer to nest in the canopy of mangroves and cypress swamps, these large waders have been threatened by the logging of wetlands across the Coastal Plain. Nevertheless, they are still rather common in some areas; on Longboat Key, Florida, they often join ibis and egrets along golf course channels or stalk prey on the mudflats of Sarasota Bay during low tide. When soaring overhead, they may be mistaken for white pelicans but their classic silhouette, with extended necks and trailing legs, aids identification.

Monday, January 25, 2010

In order to truly appreciate natural ecosystems, it is important to visit during all seasons of the year. Last week was our first mid-winter visit to Longboat Key, off Sarasota, Florida, and there were surely some unexpected observations.

Due to the effects of our economic downturn, the usual abundance of winter snowbirds, down from Canada, New England and the Upper Midwest, was markedly suppressed. Less expected was the diminished population of their natural cousins; while brown pelicans, ospreys, American white pelicans and cormorants were observed in usual numbers, most other birds, including shorebirds, gulls, terns, herons and egrets, were significantly reduced. Noting the increased number of dead fish on the bay and on the beaches, we wondered if the recent, severe cold had impacted the availability of food, causing the native and wintering flocks to disperse to other areas (especially southward). Then again, having never visited in January, perhaps our observations were in line with typical, seasonal patterns.

While nature's cycles are fairly predictable, local conditions vary widely from year to year and the temporary impact of extreme weather can lead to false conclusions. Regular observations, over many years, are essential to understanding the complex interaction of weather, flora and fauna within our natural ecosystems.

Sunday, January 17, 2010

The surface of our planet is covered by seven large and numerous smaller tectonic plates. Up to 50 miles thick, these plates are in constant motion, governed by the opening and closing of oceans. Their movement, too slow to observe during our brief life spans, is manifest by earthquakes and volcanic eruptions.

All of the larger plates are composed of both continental and oceanic crust; the latter is more dense and, in areas where continental and oceanic crust collide, the oceanic crust subducts (dips) beneath the continental crust. The line of subduction is called a trench and, as the leading edge of the oceanic crust approaches the Earth's mantle, it melts to form magma, which, in turn, rises to form volcanoes on the overlying continental plate; the Aleutian Chain, the Andes, the Cascades, Japan, the Philippines and many other island chains are examples of this process. The edge of the continental plate is pulled down by friction with the subducting, oceanic plate but rebounds intermittently, producing earthquakes in these subduction zones; tidal waves (as occured in Indonesia) may be generated if ocean water overlies the rebounding edge.

Where two areas of continental crust collide, mountain ranges form; the Himalayas, still rising as the India Plate smashes into the Eurasian Plate, is our best current example; earthquakes are common in these collision zones. In other areas, tectonic plates are scraping along one another; earthquakes, like the one in Haiti this week and the regular quakes along the San Andreas Fault of Southern California, occur when pressure is suddenly released along these transform faults. While most earthquakes occur near the margins of tectonic plates, some occur in the middle of plates, the result of rifting (e.g. the East African Rift), settling along old suture lines, volcanism above mantle plumes (e.g. Yellowstone) or stretching of crust between areas of uplift (e.g. the Great Basin of the U.S.). In reality, few, if any, areas of our planet are immune to earthquakes.

Saturday, January 16, 2010

We could hardly wait. After what seemed like a month of frigid, Arctic weather, this week's forecast called for highs in the thirties and forties (F). It would feel like spring! But, except for one sunny, mild afternoon, the promised thaw has been a gray, damp, chilly experience.

This morning, enveloped in an icy fog, we in central Missouri know that winter still grips the land. Indeed, the current bout of "seasonal conditions," with low clouds, wet streets, humid air, gray snow banks and temperatures just above freezing, are less comfortable than the frigid but dry, sunny weather of the preceding weeks. And those bright, blue skies and sparkling snowscapes were more pleasing to the eye.

We humans are always looking ahead, convinced that tomorrow will be better than today. Despite their frequent inaccuracy, we focus on long term weather forecasts, looking for a reprieve from the heat or snow, from the rain or drought. It's probably best to take one day at a time, knowing that winter is here and that spring will follow.

Thursday, January 14, 2010

Once again, the voice of evil has risen amidst a devastating human tragedy. Pat Robertson, the depraved conservative evangelist, sees God's hand in the Haiti earthquake, a punishment for that country's "pact with Satan." Such religious zealots, convinced that their God micromanages the Universe, view life from a narrow, self-righteous perspective.

Like other con men who use natural disaster to further their cause and line their pockets, religious bigots are quick to spout opinions that will appeal to their god-fearing, uneducated base of support. Robertson's poisonous and evil remarks, tinged with racism, disgust most humans but reinforce the views of his flock.

While some might argue that it is best to ignore the rant of these zealots, their message of hate, however deranged, resonates through a significant segment of human society. And their extreme views, though ridiculed by mainstream churches, highlight the danger of intolerance and rigid religious beliefs throughout the global population. In most cases, these convictions foment discrimination, impair cooperation, trigger confrontation and augment human misery; for these reasons, they must be exposed and condemned.

Wednesday, January 13, 2010

As the Atlantic Ocean began to open, some 160 million years ago, the North and South American Plates were pushed westward; this process continues today. West of these Plates was the vast Farallon Oceanic Plate and associated smaller plates and, since the Jurassic Period, most of these plates have subducted beneath the Americas, adding their cargo of exotic terrains to the Continents and producing volcanic mountain ranges; remnants of the Farallon are still activating volcanoes in the Cascades, Mexico's Volcanic Belt, western Central America and the Andes of South America today.

One of the oceanic plates, the Caribbean Plate, did not subduct but was wedged between the advancing American Plates and actually overrides those plates in some areas; indeed, along its eastern edge, the volcanic arc of the Lesser Antilles has developed as the American Plates subduct beneath the Caribbean Plate. On its northern and southern borders, the Caribbean Plate is scraping past the American Plates along slip faults, which, in some areas, are interrupted by microplates.

Yesterday, a 7.0 magnitude earthquake struck Haiti due to movement along the edge of the Gonave Microplate, which is wedged between the North American and Caribbean Plates. Since a major quake has not occurred in this country for more than a century and since Haiti is too impoverished to construct buildings that resist earthquakes, widespread damage and many fatalities have resulted. Similar events have and will occur along other slip faults across the globe, including the San Andreas Fault of Southern California; since these events are infrequent relative to the human life span, we often feel immune to their destructive power. But, despite our perception, the evolution of our planet continues.

Tuesday, January 12, 2010

Rosy finches are medium-sized songbirds of the American West that are among the most prized and most elusive quarry of avid birdwatchers. Since they nest at higher elevations than all other North American birds, rosy finches are especially difficult to observe during the warmer months. Come winter, they form large, mixed flocks and often appear in mountain towns and at ski resorts, where they feast on human handouts; during periods of heavy snow, some flocks descend to lower elevations, roosting in the crevices of rock-walled canyons.

Of the three rosy finches in North America, only the brown-capped species breeds in the mountains of Colorado; indeed, one of the best places in North America to observe this finch is at Summit Lake, along the Mt. Evans road, west of Denver. Gray-crowned rosy finches breed in mountains of the Pacific Northwest while black rosy finches summer in the high mountains of northern Utah, western Wyoming, Idaho and western Montana. Generally nesting on cliffs near open tundra, rosy finches feed on the ground, scouring alpine grasslands and snowfields for windblown seed.

During winter and early spring, all three species inhabit the high country of Colorado and, as above, are best found in mountain towns or at ski resorts; feeders at the Loveland Basin Ski Resort (at the east entrance to the Eisenhower Tunnel, on I-70) provide one of the better sites to find them close to Denver. Should severe winter weather envelop the mountains, these hardy but erratic wanderers may descend to the foothills, turning up in towns such as Estes Park, Morrison (Red Rocks Park), Woodland Park and La Vita.

Monday, January 11, 2010

Though more common during the warmer months, rufous-sided towhees can be found in the Midwest throughout the year. But even in summer, these reclusive birds are not terribly common in residential areas. Favoring brushy slopes and wood margins, they scratch for insects and seeds beneath thickets, shrubs and cedar groves.

This past week, which was characterized by frigid temperatures and extensive snow cover, a lone towhee turned up at our backyard feeder. Joining the usual assortment of suburban "feeder birds," the towhee would huddle in the sun on a nearby branch and intermittently drop beneath the feeder to feast on fallen seed; I'm sure he also took advantage of various wild berries along our wood border.

While I have seen rufuous-sided towhees on numerous occasions and have observed them in abundance across the Front Range foothills, to host this single bird, somewhat out of place among the standard cast of winter visitors, has been a special treat during an otherwise brutal week. Such events are among the special joys of having a backyard feeder; uncommon visitors or transients, attracted by the commotion of the usual suspects, make a grand appearance. Indeed, many bird watchers, including most novice birders, have found new species (for their life or backyard list) in this way.

Sunday, January 10, 2010

As severe cold has enveloped much of the Northern Hemisphere over the past few weeks, concerns about global warming have certainly been upstaged by worries related to crop damage, travel disruption and frozen pipes. Of course, temporary weather patterns have little to do with the long term climate change and global warming always receives more attention in the midst of a long, hot summer.

While there is little doubt that Earth's climate is warming and that man has played some role in the process, the welfare of natural ecosystems and of the human species is threatened by a host of factors, not all of which are under our control. Earthquakes, volcanic eruptions, tidal waves, hurricanes and other severe weather events will surely have more impact in the coming decades than the gradual change in climate and how global warming will affect weather patterns and agriculture is still open to speculation.

On the other hand, we must acknowledge the multiple negative impacts that we have on Earth's ecosystems and make every effort to minimize them. While attention to carbon emissions is certainly important, we cannot overlook the many other forms of pollution that result from human activity. And while technology and recycling may solve some of our problems, the willingness to address excess consumption, habitat destruction and uncontrolled population growth will be vital to the future welfare of our planet and our species.

Saturday, January 9, 2010

With the center of this Arctic outbreak parked over northwest Missouri, it is likely that we have now endured the coldest air of this system and, very possibly, the lowest temperature of this winter season. As I walked to work this morning, a crescent moon beamed in the clear, dark, southeast sky; it was nine degrees below zero (F) and this afternoon's high is forecast to reach ten above.

But, after a slightly less chilly night, we should be on the backside of the Arctic dome by tomorrow and southwest winds will push us into the mid twenties; on the negative side, these winds will produce a wind chill that might make it feel colder than it does today. Thawing should begin by mid week as the frigid air moves off to the east and we return to more seasonable conditions; by then, the upper thirties will feel like spring.

Prolonged, severe cold can have a depressing effect on humans, not designed to function in such weather. But native wildlife, not focused on thermometers and weather reports, took the polar air in stride. No doubt, some creatures succumbed to the brutal conditions but, for them, every day is a life and death struggle.

Thursday, January 7, 2010

Most of Earth's mountain ranges have formed due to compression within or along tectonic plates and many others are volcanic in nature, having developed above a mantle plume or along subduction zones. A third type of orogeny, fault-block mountains, rise along faults where the crust is under tension; this stretching generally occurs between areas of uplift or due to friction with other tectonic plates (often distant from the rift zone). As the crust is stretched, fault lines (some new and others old) rupture perpendicular to the line of stress and one edge of the crust slips above the other; as a consequence, fault-block mountains have a steep face along the fault and a gentler slope on their other side.

In the U.S., fault-block mountains are most common across the Great Basin, in the desert Southwest and along the Rio Grande Valley. In the Great Basin, topographic waves of these fault-block ranges, running north to south and spaced east to west, rise above high, flat desert and scrublands between the Wasatch Plateau of Utah and the Sierra Nevada of California. Among our more well known fault-block ranges are the Tetons of Wyoming (their steep edge facing east) and the Sandia Mountains east of Albuquerque, New Mexico (their steep edge facing west).

Though difficult to appreciate during our brief life span, most of these fault-block ranges continue to rise as the rifting process persists. Earthquakes are common along and near these mountains and, eventually, those of the Southwest and Great Basin are expected to become islands as ocean waters invade from the Sea of Cortez.

Wednesday, January 6, 2010

In the course of nature's year, there is a shifting balance between predator and prey. During the colder months, when food is scarce and heavy snows or ice impair mobility, the hunters have a decided advantage.

Across the north, wolf packs feast on elk, moose and deer that are weakened by the elements and stranded by the weather. In more moderate climes, owls, hawks, coyotes and fox enjoy a similar advantage; though their prey (cottontails, voles, quail) may den up during severe weather, they must eventually seek food and, when they do, these patient and well-equipped hunters are waiting. Flocking birds, especially gregarious during the winter months, are easy targets for falcons and accipiters.

Winter is, indeed, the culling season, ensuring that prey populations remain in check. And, despite the brutal conditions, it is often a less challenging season for many of the predators. But spring will arrive, greenery will spread, new generations of prey will appear and their populations will soar; then, it will be their season in the sun.

Tuesday, January 5, 2010

Looking out from our heated homes, it has been beautiful in central Missouri over the past few days. Bright sunshine, clear blue skies and a snowy landscape have produced an appealing winter scene. But outside, the beauty has come with a price: cold, dry air with temperatures in the teens and single digits.

In mid winter, the sun angle is too low to provide much heat and the clear skies, devoid of cloud cover, allow what little heat is present to escape into the upper atmosphere. Of course, this process is compounded on clear, winter nights and our overnight lows have dropped below zero F.

By tomorrow, southwest winds, ahead of the next Arctic front, will bring in clouds and snow; this combination of a southerly flow and a cloud blanket should allow our afternoon temperatures to soar into the low to mid twenties. Unfortunately, the second round of polar air, due by late in the week, will bring the coldest days and nights of the season. At least the sunshine will warm our souls.

Monday, January 4, 2010

Like birds and other mammals, humans are endotherms; our core body temperature is independent of our environment and, in order for our organ systems to function properly, it must be maintained within a rather narrow range. Heat generation is through shivering, other muscular activity and our internal metabolism. Ninety percent of our heat loss is through the skin (sweating, radiation, conduction, convection)while 10% is via the lungs; heat loss via conduction increases dramatically with water immersion and convectional heat loss is augmented by wind. If supplied with adequate food, water and shelter, a naked human adult can maintain a normal core temperature in environments ranging from 55 to 130 degrees F; beyond this range, our compensatory mechanisms are inadequate and we become hypothermic or hyperthermic (both potentially fatal conditions).

Prevention of hypothermia includes the avoidance of unnecessary exposure, intake of high-caloric food, adequate hydration and the use of warm, layered clothing (including efforts to minimize heat loss from the head and extremities); layers should be adjusted to prevent sweating, which accelerates heat loss. Use of alcohol, which promotes peripheral dilation and augments heat loss, must be avoided. Persons found to be hypothermic should be warmed with multiple blankets (after removal of wet clothing) and should not be moved any more than is absolutely necessary (movement may trigger lethal arrhythmias in a hypothermic heart). Emergency medical assistance should be sought as soon as possible and CPR should be initiated if vital signs are lost; it is important to keep in mind that some individuals with extreme hypothermia have been successfully resuscitated, often with minimal neurologic sequelae (the record low core temperature for a surviving adult is 60.8 F or 16 C).

Sunday, January 3, 2010

Male cardinals get a great deal of attention during the winter months, when their bright red plumage contrasts with barren woodlands and snowy landscapes. Indeed, these "red birds" are among the best known and favored species of the casual backyard birder.

But, from my point of view, their less glamorous partners are more attractive. Though their colors are not as bright and eye-catching, female cardinals have a beautiful, varied plumage of muted, natural tones. Dull, reddish highlights on their crests, wings and tails contrast with their soft brown back and lighter, buff colored chest and abdomen. A black facial mask, not as dark and sharp-edged as that in the male, sets off the heavy, pink-orange bill that typifies all cardinals.

As one known for a rather dull-colored wardrobe of greens and browns, I readily admit to my preference for earth tones; "loud" clothing has never appealed to me. Perhaps I'm just programmed to appreciate the more subtle beauty in nature as well.

Saturday, January 2, 2010

Some cold fronts sweep into the Midwest behind potent storm systems, as strong, northwest winds develop behind an energized low; in these cases, destructive thunderstorms often precede the front while heavy snow and blizzard conditions develop to its west. Other cold fronts, usually dropping south from the Canadian Plains, arrive with barely a whimper as dense, frigid Arctic air flows through the Heartland like a slow, broad river. Often nudged from the North Pole by a developing ridge over Alaska and western Canada, the dome of cold, dry air funnels southward between the High Plains and the Appalachians, with the most frigid air settling across the Upper Midwest.

Record low temperatures had developed across Minnesota and the eastern Dakotas this morning (as the center of the dome crossed into the U.S.) and extreme cold is forecast for most of the Midwest throughout the coming week; the leading edge of the cold air, moderating as it flows to the south and east, will bring a hard freeze to the Gulf Coast and northern Florida over the next few days.

Since the cold, dense air behind these Arctic fronts is usually rather shallow, the higher terrain of the High Plains and Front Range often escapes the most severe air, which drains southward through the Missouri and Mississippi Valleys. Today, Denver, Colorado, will be in the 40s(F) while here in Columbia, Missouri, we'll top out in the mid teens (after an overnight low of zero).

Friday, January 1, 2010

The new year arrived with a blue moon shining in the clear, cold winter sky. Of course, the moon was not actually blue in color but it was the second full moon to occur in December, 2009. Over the years, there have been a number of definitions for a blue moon, including the second full moon in a calendar month and one of four full moons (usually the third) to occur within a season. Due to its variable definition, some kind of blue moon will occur in about three of four years.

Such designations, infused with mythology, imply that the moon's orbit is somehow disrupted, perhaps by supernatural powers, to produce the "extra" event. This, of course, is an illusion; the lunar cycle is not changing, although our lone, natural satellite is gradually moving further away from the Earth. Rather, the occurrence of blue moons reflects the inexact nature of the human calendar.

Once again, man has a tendency to view nature from his own, self-important perspective. When events occur that don't fit our expectations (based on our brief life experience and limited understanding) we infuse them with mystical significance. For many, "unnatural" events are reassuring, providing evidence that there is a spiritual world beyond our physical Universe.